Whenever any municipality obtains a plant as provided in § 7-213, a commission shall be appointed, as hereinafter provided, to be known as the board of gas commissioners, board of electrical commissioners or board of gas and electrical commissioners, to whom shall be entrusted, subject to any ordinances established by such municipality, the operation, control, management and repair of plant, and the manufacture, generation and distribution of gas and electricity, including the purchase of supplies and the hiring and discharge of employees and of a suitable clerk and superintendent, and all the business relating to such manufacture, generation and distribution and to the methods, amounts, times, prices and quality of supply to each person and corporation, the collection of bills, the keeping of accounts and the custody of money received for gas or electricity, or otherwise, and the payment of bills incurred in said business. Such commission shall consist of three electors of such municipality, not holding other official positions in such municipality, who shall be appointed by the selectmen if a town, the common council if a city or the warden and burgesses if a borough, one for one year, one for two years and one for three years, and thereafter annually one commissioner shall be appointed to serve for three years. Before entering upon the duties of their office, they shall each give a bond to the municipality for the faithful performance of their duties, in such sum and form and with such sureties as the selectmen, mayor or warden and burgesses approve. The commission shall, on the first day of September of each year, render to the selectmen, common council or warden and burgesses a detailed statement of its doings and of the business and financial matters in its charge. It shall also, at any time required by the selectmen, common council or warden and burgesses, make to them a statement of its doings, business, receipts, disbursements and balances and of the indebtedness of the municipality, in its department, in the detail required, and it shall pay over to the treasurer of the municipality all moneys collected in its department. Any vacancy in such board may be filled for the unexpired portion of the term by the appointing authority.